The list of episodes of Treehouse of Horror produced by the animated television series The Simpsons. Treehouse of Horror episodes have aired annually since the second season (1990) and each episode has three separate segments. These segments usually involve the family in some horror, science fiction, or supernatural setting and always take place outside the normal continuity of the show and are therefore considered to be non-canon. "Treehouse of Horror" episode aired on October 25, 1990 and was inspired by EC Comics Horror tales. Before "Treehouse of Horror XI", which aired in 2000, every episode has aired in the week preceding or on October 31; "Treehouse of Horror II" and "Treehouse of Horror X" are the only episodes to air on Halloween. For "Treehouse of Horror", there were even three different directors for the episode. However, starting with season fifteen's "Treehouse of Horror XIV", only one writer was credited as having written a Treehouse of Horror episode, and the trend has continued since.